Sexual differences of medaka oryzias latipes in the acute toxicity test of cadmium

Sexual differences of medaka oryzias latipes in the acute toxicity test of cadmium

Kasuga S.

Nippon Suisan Gakkaishi 46(9): 1073-1076

1980

To clarify whether physiological differences of fish affect toxicity test of heavy metals, 2 groups of medaka were studied, one in which sexual maturation was induced under a long photoperiod (group L; 16L-18D, 25.degree. C) and the other where it was inhibited under a short photoperiod (group S; 8L-16D, 25.degree. C). Sexually activated females of group L had largest hepatosomatic index and sexually activated male of group L the smallest. Hepatosomatic indices for both sexes of group S were intermediate and not significantly different. In acute toxicity test of Cd, sexually activated female fish showed least susceptibility. Males were most susceptible. Both females and males of sexually inactivated fish (group S) were intermediate in susceptibility and did not differ significantly from each other. Susceptibility was correlated, not with sexual maturation, but with hepatosomatic index which indicated detoxication potential.